Method and apparatus for maintaining constant the level of filling in a charging container arranged before a consuming device for pourable material, especially plastic granulate

ABSTRACT

There is disclosed an apparatus and method for maintaining substantially constant the level of filling of pourable material, especially plastic granulate, into a charging container arranged in front of a consuming device. Thus, there is provided a charging container having at its top region a suction pipe directed away from the charging container and therebelow a conveying conduit entering into said charging container. Operatively communicating with the suction pipe and the conveying conduit is a blower or suction device. The suction conveying installation is operated at a feeding capacity which is above the material requirements of the consuming device, and the pressure at the inlet region of the consuming device is maintained such that it does not exceed the pressure in the charging container.

United States Patent Beck [ 51 May 2, 1972 [54] METHOD AND APPARATUS FORMAINTAINING CONSTANT TI-IE LEVEL OF FILLING IN A CHARGING CONTAINERARRANGED BEFOREA CONSUMING DEVICE FOR POURABLE MATERIAL, ESPECIALLYPLASTIC GRANULATE [72] Inventor: Erich Beck, Worms-Weinsheim, Germany[73] Assignee: Ingenieurbureau Dr. Brehm AG, Zurich,

Switzerland [22] Filed: Jan. 26, 1970 21 Appl. No.: 5,457

[52] 11.5. C1 ..222/56, 222/64, 222/205 [51] Int. Cl ..B67d 5/08 [58]Field ofSearch ..222/1,55,56,57,64, 193,

Primary ExaminerSamuel F. Coleman Assistant Examiner-Larry MartinAttorney-Werner W. Kleeman [5 7] ABSTRACT There is disclosed anapparatus and method for maintaining substantially constant the level offilling of pourable material, especially plastic granulate, into acharging container arranged in front of a consuming device. Thus, thereis provided a charging container having at its top region a suction pipedirected away from the charging container and therebelow a conveyingconduit entering into said charging container. Operatively communicatingwith the suction pipe and the conveying conduit is a blower or suctiondevice. The suction conveying installation is operated at a feedingcapacity which is above the material requirements of the consumingdevice, and the pressure at the inlet region of the consuming device ismaintained such that it does not exceed the pressure in the chargingcontainer.

14 Claims, 2 Drawing Figures [56] References Cited UNITED STATES PATENTS2,511,637 6/1950 Johannes ..222/205 X Patented May 2, 1972 3,659,748

W [1 K INVENTOR ATTORNEY BACKGROUND OF THE INVENTION The presentinvention relates to an improved method of and apparatus for maintainingconstant the level or degree of filling of a charging container arrangedin front ofa consumer or load for pourable material, especially plasticgranulate.

During the processing of such type materials, for instance in extrudersor injection molding equipment, it is in the interest of the uniformityand quality of the finished product, when the material always enters theload or consuming device with a constant pouring density, in other wordsnot too loose and not too compact. Therefore, attempts have been made tocontrol the filling level or degree of filling of the charging containerarranged in front of the consuming device and which is capable of beingfilled by pneumatic conveying, through the use of electrical ormechanical detectors in such a way that upon reaching a reference valuethe conveying of the material is interrupted and upon dropping below thereference value the conveying of material is again immediately placedinto operation. These known types of devices are extremely expensive,cumbersome and quite subject to disturbances or breakdown.

Furthermore, there has become known to the art a charging containerwhich is connected to a suction conveying installation and which isconstructed in the form ofa separator. This known type of device has asuction stud or conduit which leads from the top away from the chargingcontainer and further incorporates a conveying tube or conduit whichmerges into the device below the suction stud. In this arrangement atime-controlled suction blower and a discharge flap responsive to thenegative pressure in the container brings about an alternate filling ofthe container and delivery of material to the consuming device or load.Yet, maintaining the level or degree of filling of the containerconstant and continuously supplying the consuming device, as isoftentimes necessary, is not possible with this type of equipment.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of thepresent invention to provide an improved method and apparatus of theaforementioned type which efiectively overcomes the drawbacks previouslydiscussed hereinabove.

Additionally, it is a further object of the present invention to providean improved method which, in quite surprising manner, and without anyadditional control devices of an electrical and mechanical nature,renders possible maintaining the level or degree of filling ofa chargingcontainer constant, and furthermore, if desired, allows for a continuoussupply of a load or consuming device with material.

The inventive method resides in the features that there is employed forthe charging container a separator which is of known construction andwhich possesses an upwardly leading away suction tube or conduit and aconveying conduit entering therebelow, such separator being operativelyconnected to a suction feed or conveying installation. The suctionconveying or feed installation is operated at a feed capacity disposedabove the material requirements of the consuming device and the pressurein the inlet zone of the consuming device is not maintained above thepressure in the charging container. Thus, upon attaining a level offilling which is somewhat above the mouth of the conveying pipe orconduit further conveying of material is automatically stopped and onlythen restarted when the level or degree of filling has dropped again tothe opening or mouth of the conveying pipe by virtue of removal ofmaterial.

For the purpose of more exactly limiting the highest level of fillingthere can be arranged in known manner between the suction stud orconnection and the mouth of the feed or conveying pipe in the containera sieve, impact plate or like structure.

The apparatus for carrying out the inventive method becomes extremelysimple when the inlet zone merging with the charging container is sealedin pressure tight fashion towards the outside due to the construction ofthe load or consuming device. In another case and in accordance withfurther aspects of the invention, the inlet zone of the consuming deviceis formed by the negative pressure side of a pressure sluice arranged infront of the load or consuming device.

BRIEF DESCRIPTION OF THE DRAWING The invention will be betterunderstood, and objects other than those set forth above, will becomeapparent, when consideration is given to the following detaileddescription thereof. Such description makes reference to the annexeddrawing wherein:

FIG. 1 is a longitudinal sectional view of a first embodiment ofinventive apparatus; and

FIG. 2 is a longitudinal sectional view of a second embodiment ofinventive apparatus.

DETAILED DESTRIPTION OF THE DETAILED EMBODIMENTS Describing now thedrawing, it will be seen that in accordance with the arrangement of FIG.1 the consuming device or load 2 together with its inlet zone or region3 is directly connected to the charging container 1. The load orconsuming device 2 in the present instance can be assumed to be anextruder having a conveying worm 4, which in operation and in anoperationally ready condition, by virtue of its filling the inlet zone 3with material is sufficiently pressure tight sealed. Additionally, atthe outlet of the container 1 there is further arranged a blocking orlocking slide member 5, or equivalent structure. The container 1 itselfpossesses a funnel like lower portion 6 and a cylindrical upper portion7. At the top region of the container 1 it will be recognized that fromthe central area thereof there merges away the suction pipe or conduit 8which communicates the inner compartment of the container I with asuction conveying means here shown as embodying a suction blower 9.

Continuing, it will be understood that the conveying pipe or conduit 10which leads from a nonillustrated suitable supply container extends upto the central area of the charging container and is downwardly flexedat its end mouthpiece or outlet opening region ll, as shown. Further, abaffle means here shown as a sieve 12 is installed somewhat above themouth of the flexed or bent end piece 11 of the conveying or feed pipe10. Finally, at the upper portion 7 of the container 1 there isadditionally located a negative pressure valve 13 which limits to asuitable degree the possible negative pressure in the container l. Thesuction conveying installation 8-11 is designed and dimensioned suchthat its feed capacity exceeds the requirement of the extruder 2.

The mode of operation of the heretofore described apparatus is asfollows: Prior to setting the equipment into operation, in other wordswith the charging container 1 empty and with the extruder 2 empty, theslide member 5 is closed and the suction blower 9 is started intooperation. Due to the negative pressure which builds up internally ofthe container 1 the material is sucked through the feed or conveyingpipe 10 and deposits in the interior of the container 1. When thedeposited material reaches the level of the mouth of the downwardly bentend 11 of the feed pipe or conduit 10 and finally exceeds same, then theinfeed of material becomes more difficult and finally is stopped, latestwhen the material has reached the level of the sieve 12. This effect issupported by virtue of the fact that the negative pressure whichprevails in the still free sectional portion of the upper region 7 ofthe container 1 and which negative pressure continuously increases withthe difficulty of sucking material into the container 1 leads to theopening of the valve unit 13.

Now the suction blower 9 is temporarily placed out of operation and theslide member 5 at the outlet of the container lower region 6 is opened.The pressure difference between the inlet zone 3 of the extruder 2equalizes and the material arrives at the extruder 2, which is then nowplaced into operation. Since the inlet zone 3 is closed sufficiently inpressure tight fashion by virtue of the material itself, the slidemember 5 can remain open, The suction blower 9 is again started intooperation and the container 1 filled once again, in that the suctionconveying installation 8-ll is operated with a feeding or conveyingcapacity which exceeds the continuous delivery of material into theextruder 2. Upon reaching the maximum degree of filling, the furtherinfeed of material is again interrupted in the previously explainedmanner, but is also immediately started up again when, by virtue of theconsumption of the material, there occurs a dropping of the level offilling which, in turn, sufficiently frees the opening or mouth of theconveying or feed pipe 10, 11. With increasing filling of the containerthe delivery of material into the container is slowed down and with thefilling level dropping is accelerated. In so doing, it has been foundthat the material tends to compactly pile up in a layer beneath thesieve 12, provided that such material is not located too far above theopening or mouth of the end piece 11 of the conveying or feed tube 10.In this manner, the degree of filling oscillates between two quitenarrow limits, that is to say, during the entire operation of theextruder 2 it is maintained constant with sufficiently accuracy forpractical requirements.

The mode of operation of the apparatus for a discontinuous orintermittent operation of the load or consuming device is analogous,provided that its inlet zone is only sufficiently pressure tight sealedin that the momentary discharge out of the charging container uponfreeing of the mouth of the conveying tube is immediately againequalized. When using a consuming device or load, which from the outset,in other words also in the empty condition, at least is pressure tightat its inlet region or zone, then the placing into operation of suchequipment is considerably simpler.

In place of the previously mentioned locking or blocking slide member 5,there can of course be used other type of structure, for instance suchas a flap member. Likewise, just as was the case of briefly interruptingthe suction action by placing the blower 9 out of operation, it wouldalso be possible to interrupt this suction action by providing a flapmember or equivalent structure in the suction tube 8.

Considering now the apparatus structure depicted in FIG. 2, it will beseen or at least understood that here one is concerned with a load orconsuming device 14 which in itself is not sufficiently pressure tight.It is for this reason that there is arranged between the load orconsuming device 14 and the container lower portion 6 a suitable bucketwheel sluice or lock 15.

The return side of the sluice 15 is used for balancing the pressure inthe empty compartments 16 of the bucket wheel 17 which revolves in thedirection of the indicated arrow and the negative pressure in thecharging container 1 is communicated with its upper portion 7 by aconduit 18. In contrast to the first embodiment, in this case the feedor conveying pipe 19 enters tangentially, as shown, so that theseparation of the conveyed material is enhanced by the centrifugalaction, and the suction tube 20 is extended into the container 1 throughthe utilization ofa sieve basket 21 or equivalent structure. Just as isthe case with the first embodiment, here also at the upper region 7 ofthe container 1 there is provided a negative pressure valve arrangement13.

In order to place the apparatus into operation during standstill orinoperativeness of the consuming device 14 and the bucket wheel 17 thecontainer 1 is filled by the suction conveying installation 9, 19, 20.This occurs until filling thereof has reached the highest level afterexceeding the mouth of opening of the conveying tube 19 and considerablycovering the sieve basket 21. When this occurs the filling operation isinterrupted. Now if the sluice l5 and the consuming device 14 are placedinto operation, then the removal of the filling level in the container 1is continuously balanced exactly as in the case of the first example orembodiment. Actually, the same also holds true here for a continuous aswell as for a discontinuous mode of operation of the consuming device orload.

Of course, in accordance with the inventive method there can be used toadvantage a number of consuming devices by means of a similar number ofcharging containers which are supplied by a common supply container oralternately from a number of supply containers, and wherein, it isreadily possible to place out of operation one or the other of theseloads or consuming devices. in this instance it is advantageous if thecharging containers are all or in groups connected in operableassociation with a common suction conduit.

While there is shown and described present preferred embodiments of theinvention, it is to be distinctly understood that the invention is notlimited thereto but may be otherwise variously embodied and practicedwithin the scope of the following claims.

What is claimed is:

1. An apparatus for maintaining constant the level of filling ofpourable material, especially plastic granulate, into a chargingcontainer, comprising a consuming device, a charging container arrangedin front of said consuming device, a suction pipe arranged at the upperregion of said charging container and directed away from said chargingcontainer, a conveying conduit means having an outlet opening disposedwithin the interior of said charging container, a suction conveyingmeans communicating with said suction pipe and said conveying conduitmeans for drawing by suction pourable material through said conveyingconduit means into said charging container, and baffle means arrangedwithin said charging container between said suction pipe and the outletopening of said conveying conduit means into said charging container,said pourable material upon rising at least to the level of said bafflemeans and after reaching a point above said outlet opening of saidconveying conduit means acting as a closure for said out let openingthereby preventing the suction from continuing to draw pourable materialthrough said conveying conduit means into said charging container.

2. An apparatus as defined in claim 1, wherein said baffle meanscomprises at least one sieve member.

3. An apparatus as defined in claim 2, wherein said sieve member isconstructed as a sieve basket which provides an extension of saidsuction pipe into the interior of said charging container.

4. An apparatus as defined in claim 3 wherein said suction pipe iscentrally located at the top region of said charging contamer.

5. An apparatus as defined in claim 1, further including means definingan inlet region for said consuming device and which communicates withsaid charging container and in operation therewith is sealed in pressuretight fashion towards the outside.

6. An apparatus as defined in claim 1, wherein said conveying conduitenters into said charging container up to approximately the centralregion thereof and incorporates an end portion which is downwardly bent,said downwardly bent end portion containing said outlet opening which isdirected away from said baffle means.

7. An apparatus defined in claim 1, wherein said conveying conduitincorporates a terminal portion which tangentially merges with saidcharging container.

8. Apparatus as defined in claim 1, further including valve meansarranged at the upper region of said charging container whichautomatically limit the negative pressure.

9. An apparatus as defined in claim I, wherein a multiplicity ofcharging containers are operatively connected to a c0mmon suctionconduit either collectively or in groups.

10. An apparatus for maintaining constant the level of filling ofpourable material, especially plastic granulate, into a chargingcontainer, comprising a consuming device, a charging container arrangedin front of said consuming device, a suction pipe arranged at the upperregion of said charging container and directed away from said chargingcontainer, a conveying conduit means having an outlet opening disposedwithin the interior of said charging container, a suction conveyingmeans communicating with said suction pipe and said conveying conduitmeans, and baffle means arranged within said charging container betweensaid suction pipe and the outlet opening of said conveying conduit meansinto said charging container, said consuming device incorporating meansdefining an inlet region, said inlet region being formed by pressuresluice means arranged in front of said consuming device at the negativepressure side thereof.

11. An apparatus as defined in claim 10, wherein said pressure sluicemeans forming said inlet region of said consuming device is defined by abucket wheel sluice which incorporates empty compartments, said emptycompartments defining said inlet region of said consuming device.

12. A method of maintaining substantially constant the level of fillingof pourable material and ensuring for essentially uniform compaction ofsuch pourable material, especially plastic granulate, into a chargingcontainer arranged forwardly of a consuming device, comprising the stepsof: drawing by suction the pourable material into the chargingcontainer, filling the pourable material within the charging containeruntil reaching a predetermined level within such charging container,upon reaching such predetermined level of the pourable materialutilizing the attained level of the pourable material to counteract theeffect of the suction and to act as a closure thereby preventing thesuction from continuing to draw new material into the container tothereby shut-off the inflow of additional material into the container,withdrawing material from the container, and upon the level of thematerial falling below said predetermined level again generating asuction condition within the container sufficient to enable new materialto be drawn into the container until reaching the aforesaidpredetermined level, and continuously automatically either shutting-offthe infeed of new material into the container when the pourable materialhas reached said predetermined level or feeding new material into thecontainer whenever such pourable material falls below said predeterminedlevel, to thereby maintain a constant filling level of pourable materialwithin the container and uniform compaction ofthe material within thecontainer.

13. The method as defined in claim 12, further including the step ofcontrolling the suction drawing material into the charging containersuch that the feeding capacity for new material into the chargingcontainer generated by the suction effect is above the materialrequirements of the consuming device, and maintaining the pressure atthe inlet region of the consuming device such that it does not exceedthe pressure prevailing in the charging container.

14. The method as defined in claim 12, including the step ofprogressively throttling to shut-off the inflow of new material into thecharging container owing to the progressive rise of such material withinthe charging container towards said predetermined level.

1. An apparatus for maintaining constant the level of filling ofpourable material, especially plastic granulate, into a chargingcontainer, comprising a consuming device, a charging container arrangedin front of said consuming device, a suction pipe arranged at the upperregion of said charging container and directed away from said chargingcontainer, a conveying conduit means having an outlet opening disposedwithin the interior of said charging container, a suction conveyingmeans communicating with said suction pipe and said conveying conduitmeans for drawing by suction pourable material through said conveyingconduit means into said charging container, and baffle means arrangedwithin said charging container between said suction pipe and the outletopening of said conveying conduit means into said charging container,said pourable material upon rising at least to the level of said bafflemeans and after reaching a point above said outlet opening of saidconveying conduit means acting as a closure for said outlet openingthereby preventing the suction from continuing to draw pourable materialthrough said conveying conduit means into said charging container.
 2. Anapparatus as defined in claim 1, wherein said baffle means comprises atleast one sieve member.
 3. An apparatus as defined in claim 2, whereinsaid sieve member is constructed as a sieve basket which provides anextension of said suction pipe into the interior of said chargingcontainer.
 4. An apparatus as defined in claim 3 wherein said suctionpipe is centrally located at the top region of said charging container.5. An apparatus as defined in claim 1, further including means definingan inlet region for said consuming device and which communicates withsaid charging container and in operation therewith is sealed in pressuretight fashion towards the outside.
 6. An apparatus as defined in claim1, wherein said conveying conduit enters into said charging container upto approximately the central region thereof and incorporates an endportion which is downwardly bent, said downwardly bent end portioncontaining said outlet opening which is directed away from said bafflemeans.
 7. An apparatus defined in claim 1, wherein said conveyingconduit incorporates a terminal portion which tangentially merges withsaid charging container.
 8. Apparatus as defined in claim 1, furtherincluding valve means arranged at the upper region of said chargingcontainer which automatically limit the negative pressure.
 9. Anapparatus as defined in claim 1, wherein a multiplicity of chargingcontainers are operatively connected to a common suction conduit eithercollectively or in groups.
 10. An apparatus for maintaining constant thelevel of filling of pourable material, especially plastic granulate,into a charging container, comprising a consuming device, a chargingcontainer arranged in front of said consuming device, a suction pipearranged at the upper region of said charging container and directedaway from said charging container, a conveying conduit means having anoutlet opening disposed within the interior of said charging container,a suction conveying means communicating with said suction pipe and saidconveying conduit means, and baffle means arranged within said chargingcontainer between said suction pipe and the outlet opening of saidconveying conduit means into said charging container, said consumingdevice incorporating means defining an inlet region, said inlet regionbeing formed by pressure sluice means arranged in front of saidconsuming device at the negative pressure side thereof.
 11. An apparatusas defined in claim 10, wherein said pressure sluice means forming saidinlet region of said consuming device is defined by a bucket wheelsluice which incorporates empty compartments, said empty compartmentsdefining said inlet region of said consuming device.
 12. A method ofmaintaining substantially constant the level of filling of pourablematerial and ensuring for essentially uniform compaction of suchpourable material, especially plastic granulate, into a chargingcontainer arranged forwardly of a consuming device, comprising the stepsof: drawing by suction the pourable material into the chargingcontainer, filling the pourable material within the charging containeruntil reaching a predetermined level within such charging container,upon reaching such predetermined level of the pourable materialutilizing the attained level of the pourable material to counteract theeffect of the suction and to act as a closure thereby preventing thesuction from continuing to draw new material into the container tothereby shut-off the inflow of additional material into the container,withdrawing material from the container, and upon the level of thematerial falling below said predetermined level again generating asuction condition within the container sufficient to enable new materialto be drawn into the container until reaching the aforesaidpredetermined level, and continuously automatically either shutting-offthe infeed of new material into the container when the pourable materialhas reached said predetermined level or feeding new material into thecontainer whenever such pourable material falls below said predeterminedlevel, to thereby maintaiN a constant filling level of pourable materialwithin the container and uniform compaction of the material within thecontainer.
 13. The method as defined in claim 12, further including thestep of controlling the suction drawing material into the chargingcontainer such that the feeding capacity for new material into thecharging container generated by the suction effect is above the materialrequirements of the consuming device, and maintaining the pressure atthe inlet region of the consuming device such that it does not exceedthe pressure prevailing in the charging container.
 14. The method asdefined in claim 12, including the step of progressively throttling toshut-off the inflow of new material into the charging container owing tothe progressive rise of such material within the charging containertowards said predetermined level.